Holddown shock absorbers for the mold board of an earth grader



July 27, 1965 B. E. MOORE 3,197,188

HOLDDOWN SHOCK ABSORBERS FOR THE MOLD BOARD OF AN EARTH GRADER Filed Aug. 2, 1963 2 Sheets-Sheet l B. E. MOORE 3,197,188

HOLDDOWN SHOCK ABSORBERS FOR THE MOLD BOARD OF AN EARTH GRADER July 27, 1965 2 Sheets-Sheet 2 Filed Aug. 2, 1963 q t? @wX aaz United States Patent 3,197,188 HOLDDDWN SHGCK ABSORBERS FOR TIE MOLD BOARD OF AN EARTH GRADER Burdette E. Moore, Williamsville, N.Y., assignor to Shocks, Incorporated, Buffalo, N .Y., a corporation of New York Filed Aug. 2, 1963, Ser. No. 299,548 2 Claims. (Cl. 2671) This invention relates to holddown shock absorbers for the mold board of a grader which is moved along the ground to level earth, stone, snow, ice or other solids, and is more particularly directed to such devices which serve to hold the mold board at grade for the particular surface required and at the same time permit the mold board to raise against an adjustable preload when the mold board encounters a too resistive obstacle or other type of resistance.

One of the objects of the present invention is to provide such holddown shock absorbers which will not let the mold board drop below grade but at the same time have preloaded resistance against the mold board rising above grade.

Another object of the invention is to provide such holddown shock absorbers in which there is less need for continuous mold board adjustment to compensate for high spots, since the holddown shock absorbers will start to yield when subjected to overload and give the operator ample warning before the drive wheels of his grader, particularly if a tandem axle grader, start to spin out because of being unable to move the load.

Another object is to provide such holddown shock absorbers which indicate when the mold board is on grade since at this time the mold board is working but at the same time the holddown shock absorbers are fully extended and not under compression.

Another object of the invention is to provide such holddown shock absorbers which enable the operator to attain grade with much less effort and far less wear and tear on the grader since the holddown shock absorbers cause the mold board automatically to seek the grade for which the mold board is set.

Another object of the invention is to materially reduce backlash from controls on those graders where backlash can occur.

Another object is to provide such holddown shock absorbers where back pressure in excess of normal can easily be provided, such as on one corner of the mold board when rooting out rocks, roots, and pieces of old pavement and the like which require a considerably greater preload pressure at that corner of the mold board.

Conversely, another object is to provide such holddown absorbers in which the preload can easily be reduced below normal, such as in shoulder cutting, where the operator wants the mold board to ride the pavement without digging or gouging into the same.

Another object of the invention is to provide such holddown shock absorbers which have an extensible leg for bank cutting and sloping while still retaining the shock absorber action fully efiective in such extended positions.

Another object is to provide a simple and effective adjustment for rendering the holddown shock absorbers completely inoperative, such as when changing tires or the like.

Another object is to provide such holddown shock absorbers which are readily adjustable to cut to grade, but cannot drop below grade when encountering a soft spot, and also yieldingly resist movement of the mold board above grade both to permit bringing the surface to grade in a series of passes or to warn the operator that a too resistive obstacle has been encountered.

3,197,188 Patented July 27, 1965 Another object is to provide such holddown shock absorbers which are low in cost and rugged in construction and will stand up under condition of severe and constant use without getting out of order or requiring repairs.

Other objects and advantages of the invention will be apparent from the following description and drawings in which:

FIG. 1 is a perspective view of a grader equipped with a pair of holddown shock absorbers embodying the present invention.

FIG. 2 is a vertical longitudinal central section through one of the shock absorbers and showing the same at minimum extension of its length.

FIG. 3 is a fragmentary vertical section taken generally on line 3-3, FIG. 2.

FIG. 4 is a fragmentary horizontal section taken generally on line 4-4, FIG. 2.

FIG. 5 is a retainer cage for a compressed spring'furnished with the holddown shock absorbers for holding the shock absorber spring under compression while extending or diminishing the eifective length of the hold- 7 down shock absorber.

FIGS. 6, 7, 8 and 9 are fragmentary side elevational views of a holddown shock absorber showing the manner in which the retaining cage illustrated in FIG. 5 is used in extending or diminishing the length of the holddown shock absorber.

FIG. 10 is a view similar to FIGS. 6-9 and showing the manner in which each holddown shock absorber is rendered inoperative, such aswhen changing a tire.

A conventional tandem axle grader is shown in FIG. 1 having an arching chassis 15, the lower front end Olf which is supported by a pair of front rubber tired wheels 16 and the lower rear end of which is supported by two pairs of tandem axle rubber tired wheels 18, 19 one or both of which can be drive wheels. The lower rear end of the chassis also supports the propelling motorshown as enclosed by a hood 20, and a cab from which the operator controls the grader. The horizontal mold board 21 is adjustably mounted for vertical and transverse horizontal angularity on the rear end of an arm 22 the forward end of whichis pivoted in any suitable manner(not shown) to the lower front end of the chassis 15, the mold board being arranged below the upwardly arching portion of this chassis.

On each side of this upwardly arching portion of the chassis 15 a stud 25, FIG. 3, projects horizontally outwardly generally at right angles to the line of movement of the grader and each of these studs has its outboard end in the form of an integral ball 26 which forms part of a balland-socket attachment to a corresponding holddown shock absorber indicated generally at 28, two of such shock absorbers being employed, one at each side of the chassis. The lower end of each shock absorber 28 has a ball-andsocket connection with the integral ball end 29 of a stud 30 projecting horizontally and laterally outwardly from the corresponding side of the free end of the'arm 22 carrying the mold board 21.

Each of the shock absorbers 28 comprises a tube having its upper end externally threaded, as indicated at 36, and secured, as by welding 38, to a lower half bearing 39 and has a semispherical bearing surface 40 mating with or engaging the underside of the corresponding ball 26. Each ball-and-socket bearing is completed by an upper half bearing 41 having a semispherical bearing face 42 mating with or engaging the top 'half of the ball 26 and secured to the lower half bearing 39 by a pair of bolts 43 or in any other suitable manner.

The tube 35is provided at its lower end with a pair of longitudinal slots 45 in its opposite side walls, these 9 slots being in radial register with each other and of the same etlective length. Below these slots 45 the tube 35 is provided with a pair of circulatr holes 46 through its opposite side walls, these holes being in axial alinement with each other radially of the tube 35.

Each holddown shock absorber also includes a cylindrical rod 50 slidingly fitting into the open lower end of the tube 35 and secured at its lower end, as by welding 51, to an upper half bearing 52 mating with or engaging the upper side of the corresponding ball 29, having a semispherical bearing surface 53 for this purpose. Each ball-and-socket bearing is completed by a lower half bearing 54 having a semispherical bearing face 55 engaging the bottom half of the ball 29 and secured to the upper half bearing 52 by a pair of bolts 56 or in any other suitable manner.

The resistance of each shock absorber is provided by a helical compression spring 60 surrounding the tube 35 and having its upper end compressed against an adjusting nut 61 on the threads 36 and which can be turned by means of a spanner wrench (not shown), the nut having radially outwardly opening holes 62 in its sides for this purpose. The lower end of the helical compression spring 6tl: seats against a ring 63 which in turn seats against a cross pin 64 which projectsthrough the slots 45 in the tube 35 and also through one of a series of transverse holes 65, 66 and 67 in the rod 50, these holes being parallel with each other and at different elevations to permit of adjusting the effective length of the shock absorber as hereinafter described. Each end of the pin-64 is provided with a transverse cotter pin 70, 71 of the hairpin type to prevent its accidentally being dislodged, and one end of this pin 64 is also beveled, as indicated at 72, and its opposite end knurled, as indicated at 73 to facilitate manual insertion of the pin 64 in any of the holes 65, 66 and 67.

Each rod 50 is provided with a second series of transverse through bores 75, 76, 78 at different elevations, these being in a radial plane perpendicular to the plane of bores 65, 66 and 67 and being arranged to register with the alining holes 46 at the lower end of the tube 35. These .holes .6 are adapted, when alined with one of the transverse bores 75, 76 and 78 of the rod 50, to receive a locking pin 79. This locking pin is only used when the holddown shock absorber is to be rendered inoperative and is shown for easy manual insertion and removal as having oneend beveled as indicated at 80 and its other end knurled as indicated at 81.

An important adjunct to the holddown shock absorber is the tool illustrated in perspective in FIG. and which is used to hold the helical compression spring 69 under compression while the effective length of each holddown shock absorber 28 is being increased or decreased. This tool is in the form of retainer cage 32 for the compressed spring 60, and comprising a top bar 83 and a bottom bar 84, the opposite ends of these bars being connected by long tie bolts 85.

The spring 69 is under preload, the degree of preload being determined by the adjustment of the nut 61 along the threads 36. This pressure of the helical compression spring 60 urges the ring 63 and cross pin 64 downwardly against the bottom of the pair of slots 45 thereby to hold the rod 50 in its extended position. This thereby urges the mold board 21 downwardly to a set position, this position being the grade which the mold board is to provide in moving over earth, stones, snow, ice or other solids to be graded.

When the mold board encounter excessive resistance, this resistance to forward movement of the grader is translated into an upward movement of the mold board 21 and by the operator without change in adjustment of the two holdown shock absorbers 28. On the other hand if some immovable object is encountered the operator is apprized of the existance of such an object before the blade rides up sufficiently far to bottom the shock absorbers and lift the front wheels 16 of the grader from the ground so as to cause them to be inoperative for steering. Before this happens the operator can stop the grader, and inspect the nature of the immovable obstacle and determine what should be done about it.

If the immovable obstacle should be a rock, root or some other object which can be removed through the use of one lower corner of the mold board 21, that side of the mold board can be lowered and the back pressure against it increased as follows:

For this purpose it is first necessary to compress the spring 66 of the holddown shock absorber to be extended, the normal extended position of the holddown shock absorber being illustrated in FIG. 6. This can be done by forcing the control arm 22 upwardly thereby to elevate the pin 64 of the holddown shock absorber to be adjusted from the bottom of its pair of slots 45, as illustrated in FIG. 7. The retainer cage 82 for the compression spring 60 shown in FIG. 5 is employed. For such use, as illustrated in FIG. 8, its top cross bar 83 is slipped over the top face of. the nut 61 at one side of the compressed shock absorber spring 60 and its lower bar 84 is slipped under the underface ofthe ring 63. The shock absorber is then released, as illustrated in FIG. 8, and vthe helical compression spring 60 reacts to force the ring 63 against the bottom cross bar 84 of the retainer cage 82, this rendering the helical compression spring inoperative so that the cross pin 64 can be removed.

This is done by removing the cotter pin 70 and pulling the pin 64 out of the slots 45 in the tube 35 as well as out of the cross bore of the rod 50. The holddown in which the shock absorber can be extended to its maxii mum extent, the cross bore 67 having been selected. For this adjustment this cross bore 67 is brought into line with the slots 45 and the pin 641 reinserted through these slots 45 and cross bore 67, and the cotter pin reapplied. Pressure through the arm 22 is then. being appiied against the shock absorber to bring the pin 64 into contact with the underside of the ring 63 with sufiicient pressure to raise this ring against the resistance of the helical compression spring 60 and to tree it from the lower cross bar 84 of the spring retainer cage82. It will be seen that the holddown shock absorber has now been extended in the length from the condition shwn in PEG. 6 to the condition shown in FIG. 9 and is fully operative, the preload or back pressure of the helical compression spring 60 not, however, having been changed.

If it is desired to increase this back pressure for the assumed purpose of rooting a root or boulder, a spanner wrench (not shown) is applied to the nut 61 and it is screwed along the threads 36 toward the cross pin 64 so as to increase the compression of the spring interposed therebetween. -When the required amount of preload has been obtained, the mold board is in condition for rooting out the obstructing stone or root following which the holddown shock absorber can be restored to normal grading used by contracting it from the length shown in FIG. 9 to, say, the length shown in FIG. 6 and reducing the preload pressure of the spring 60 by backing up the nut 61.

If for any purpose it is desired to render either or both of the holddown shock absorbers 28 completely inoperative, this can readily be done by using the pin 79 which can be inserted through the round holes 46 in the corresponding tube 35 and through any of the three transverse bores 75, 76, 78 in the rod 50 brought into alinement therewith. Whn this is done, as illustrated 5 in FIG. 10, it will be seen that the tube 35 and rod 50 are held in fixed relation to each other by this pin 29 and hence the holddown shock absorber 28 is rendered completely inoperative as a shock absorber and is merely in the form of a straight or stiff arm.

From the foregoing it will be seen that the present invention provides a very simple and rugged holddown shock absorber for use with the mold board of a grader and accomplishes the various objects and has the numerous advantages previously set forth.

I claim:

1. A holddown shock absorber for use between the mold board supporting arm structure and chassis structure of a grader, comprising a tube open at one end, means movably connecting the opposite end of said tube to one of said structures, said opposite end of said tube being externally threaded, a rod having one end slidingly fitted in said tube, means movably connecting the opposite end of said rod with the other of said structures, said tube being provided with slots in its opposite side walls in diametral register with each other and of substantially the same effective length, said rod being provided with a series of transverse through bores spaced longitudinally along said, rod and arranged to register selectively with said slots, a pin inserted through said slots and the through bore registering therewith with its ends protruding beyond said slots, a ring surrounding said tube between its threaded end and said pin and seated against the protruding ends of said pin, a helical compression spring coaxially surrounding said rod and tube having one end compressively seated against said ring, and a nut screwed on the threads of said tube and against which the other end of said helical compression spring is compressively seated whereby adjustment of said nut adjusts the preload of said helical compression spring.

2.. A holddown shock absorber as set forth in claim 1 wherein said rod is provided with a second series of through bores spaced longitudinally thereof and said tube is provided through at least one side with a transverse through bore arranged to register with any one of said second series of transverse through bores, and a second pin inserted selectively through said transverse through bore of said tube into any one of said second series of through bores to fix said rod and tube in diiferent extended positions with reference to each other.

References Cited by the Examiner UNITED STATES PATENTS 2,215,238 9/40 Wert 267-70 X 2,851,904 9/58 Banek 26770 X 2,852,958 9/58 Banek 26770 X 2,912,233 11/59 Gergely 2671 ARTHUR L. LA POINT, Primary Examiner. 

1. A HOLDDOWN SHOCK ABSORBER FOR USE BETWEEN THE MOLD BOARD SUPPORTING ARM STRUCTURE AND CHASSIS STRUCTURE OF A GRADER, COMPRISING A TUBE OPEN AT ONE END, MEANS MOVABLY CONNECTING THE OPPOSITE END OF SAID TUBE TO ONE OF SAID STRUCTURES, SAID OPPOSITE END OF SAID TUBE BEING EXTERNALLY THREADED, A ROD HAVING ONE OF END SLIDINGLY FITTED IN SAID TUBE, MEANS MOVABLY CONNECTING THE OPPOSITE END OF SAID ROD WITH THE OTHER OF SAID STRUCTURES, SAID TUBE BEING PROVIDED WITH SLOTS IN ITS OPPOSITE SIDE WALLS IN DIAMETRAL REGISTER WITH EACH OTHER AND OF SUBSTANTIALLY THE SAME EFFECTIVE LENGTH, SAID ROD BEING PROVIDED WITH A SERIES OF TRANSVERSE THROUGH BORES SPACED LONGITUDINALLY ALONG SAID, ROD AND ARRANGED TO REGISTER SELECTIVELY WITH SAID SLOTS, A PIN INSERTED THROUGH SAID SLOTS AND THE THROUGH BORE REGISTERING THEREWITH WITH ITTS ENDS PROTRUDINGG BEYOND SAID SLOTS, A RING SURROUNDING SAID TUBE BETWEEN ITS THREADED END AND SAID PIN AND SEATED AGAINST THE PROTRUDING ENDS OF SAID PIN, A HELICAL COMPRESSION SPRING COAXIALLY SURROUNDING SAID ROD AND TUBE HAVING ONE END COMPRESSIVELY SEATED AGAINSTT SAID RING, AND A NUT SCREWED ON THE THREADS OF SAID TUBE AND AGAINST WHICH THE OTHER END OF SAID HELICAL COMPRESSION SPRING IS COMPRESSIVELY SEATED WHEREBY ADJUSTMENT OF SAID NUT ADJUSTS THE PRELOAD OF SAID HELICAL COMPRESSION SPRING. 